Twenty Twelve: add print styles to stylesheet

[lancewillett]

Add a media block to main stylesheet to format print output nicely, Twenty Eleven has a great example to use as a starting point.

Goal is to keep it simple and readable.

[obenland]

Iteration 1

[obenland]

21377.diff​ adds print styles. Probably needs to be revisited after #21379 No. 2 was addressed.

[lancewillett]

Iteration 1 looks good, just a few tiny syntax errors like text-align: left: (should be semi-colon) and adding in the =Print comment header to the new block.

[lancewillett]

In [21392]:

Twenty Twelve: add print styles to stylesheet, first pass props obenland. See #21377.

[SergeyBiryukov]

Combine similar styles

[lancewillett]

In [21410]:

Twenty Twelve: update print styles to merge similar rules, props SergeyBiryukov, see #21377.

[lancewillett]

Reviewing with drewstrojny:

• Make entry meta text color a bit darker
• Remove underline text-decoration under links

[lancewillett]

In [21427]:

Twenty Twelve: print style tweaks for footer meta and link underlines. See #21377.

[lancewillett]

Print stylesheets are good for v 1.0. We can fix bugs in new tickets.